As is known, the impact-resistant vinylaromatic copolymers containing an ethylenically unsaturated nitrile exhibit, as compared with the common or conventional impact-resistant polystyrenes, improved mechanical properties and, above all, a better resistance to cracking under load in the presence of chemical agents, such as, e.g., fluorinated products.
These copolymers are therefore suitable for the manufacture of cells of refrigerators which are to be formed on the back with foamed polyurethane, the foaming agent for which is based on trichlorofluoromethane.
However, these copolymers are not equally satisfactory for utilizations which require a high resistance to high temperatures along with a good cracking resistance in the presence of fatty substances, such as oil, margarine and other fats.